The country aims to double the share of gas in its overall energy mix to more than 8 per cent by 2015.

Under Wednesday's deal, ConocoPhillips and PetroChina will also study the potential for unconventional resource development in the 500,000 acre Neijiang-Dazu Shale formation in the Sichuan Basin in southwestern China.

Financial details of the deal were not disclosed.

Shares of Houston-based Conoco were down 1 per cent at $57.97 on the New York Stock Exchange on Wednesday.